A second approach identifies Seiberg-Witten integrable systems for a large class of 4d \(\mathcal {N}=2\)  supersymmetric field theories as Hitchin systems on Riemann surfaces with tame/wild ramified punctures. This class of 4d \(\mathcal {N}=2\)  supersymmetric field theories are known as class-S theories [1]}. A precursor to this approach is the M-theory solution to certain 4d \(\mathcal {N}=2\)  quiver gauge theories engineered with D4-NS5-D6 brane systems [2]}.
